Efficacy of GnRH Immunocontraception of Wild White-Tailed Deer in New Jersey

Safe and effective contraceptive agents are needed to manage overabundant populations of cervids in settings where traditional management methods such as hunting are prohibited or impractical. We used GonaCon™ Immunocontraceptive Vaccine to reduce reproduction in individual white-tailed deer (Odocoileus virginianus) on a fully fenced corporate-office campus in suburban New Jersey, USA. In July– August 2005, we captured, marked, injected, and released 47 adult females and then monitored their reproductive performance for 2 years. Thirty-two of these females each received a 1.0-mL injection of GonaCon vaccine, and 15 control females were given sham injections. Field observations of udder condition during summers of 2006 and 2007 were used to determine which adult female deer were lactating; lactation was used as an indicator of imminent or recent parturition. During summer 2006, 8 of 24 GonaCon-treated deer were pregnant, in contrast to 12 of 13 control deer. During summer 2007, 2 years after injections were given, 13 of 23 GonaCon-treated and 10 of 12 control animals were pregnant. We also captured, vaccinated, and released fawns (both sexes) and yearling and adult males and then monitored their reproductive status. Immunocontraception of fawns was unsuccessful. In some GonaCon-treated males (all age classes), serum testosterone concentrations and development of testes and antlers were reduced. Higher anti-gonadotropin releasing- hormone antibody titers were associated with greater infertility in females and with lower values for reproductive parameters in males. GonaCon reduced reproduction in wild adult female white-tailed deer, but greater contraceptive efficacy may be required for it to gain widespread acceptance and use by natural resource managers